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Magnetism of NaYbS2: From finite temperatures to ground state

Science China(Physics,Mechanics & Astronomy) 2024年第10期Mechanics & Astronomy) .卷 96-108页

作者： Weizhen Zhuo Zheng Zhang Mingtai Xie Anmin Zhang Jianting Ji Feng Jin Qingming Zhang school of Physical Science and Technology Lanzhou University Beijing national Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences

Rare-earth chalcogenide compounds ARECh2（A=alkali or monovalent metal,RE=rare earth,Ch=O,S,Se,Te） are a large family of quantum spin liquid（QSL） candidate ***2is a representative member of the *** key issues on NaYbS2,particularly how to determine the highly anisotropic spin Hamiltonian and describe the magnetism at finite temperatures and the ground state,remain to be *** this paper,we conducted an in-depth and comprehensive study on the magnetism of NaYbS2from finite temperatures to the ground ***,we successfully detected three crystalline electric field（CEF） excitation energy levels using low-temperature Raman scattering *** them with the CEF theory and magnetization data,we worked out the CEF parameters,CEF energy levels,and CEF *** further determined a characteristic temperature of ～40 K,above which the magnetism is dominated by CEF excitations while below which the spinexchange interactions play a main *** characteristic temperature has been confirmed by the temperature-dependent electron spin resonance（ESR） ***-temperature ESR experiments on the dilute magnetic doped crystal of NaYb0.1Lu0.9S2further helped us to determine the accurate ***,we quantitatively obtained the spin-exchange interactions in the spin Hamiltonian by consistently simulating the magnetization and specific heat ***,the above studies allow us to explore the ground state magnetism of NaYbS2by using the density matrix renormalization *** combined numerical calculations and experimental results to demonstrate that the ground state of NaYbS2is a Dirac-like QSL.

关键词： anisotropic spin Hamiltonian quantum spin liquid rare-earth chalcogenide

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Rational Solutions of First Order Algebraic Ordinary Differential Equations

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Journal of Systems Science & Complexity 2024年第2期37卷 567-580页

作者： FENG Shuang SHEN Liyong school of Physical and Mathematical sciences Nanjing Tech UniversityNanjing 211816China school of Mathematical sciences University of Chinese Academy of SciencesBeijing 100049China

Let f(t,y,y')=∑ _(i=0)^(n )a_(i)(t,y)y'^(i)=0 be an irreducible first order ordinary differential equation with polynomial *** in 1998 proved that there exists a constant C such that every rational solution of f(t,y,y')=0 is of degree not greater than *** show that this degree bound C depends not only on the degrees of f in t,y,y' but also on the coefficients of f viewed as the polynomial in t,y,y'.In this paper,the authors show that if f satisfies deg(f,y)0,then the degree bound C only depends on the degrees of f in t,y,y',and furthermore we present an explicit expression for C in terms of the degrees of f in t,y,y'.

关键词： Degree bound first order AODE height rational solution

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Simulation Study on Constraining Gravitational Wave Propagation Speed by Gravitational Wave and Gamma-ray Burst Joint Observation on Binary Neutron Star Mergers

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Research in Astronomy and Astrophysics 2024年第8期24卷 42-51页

作者： Jin-Hui Rao Shu-Xu Yi Lian Tao Qing-Wen Tang Department of Physics School of Physics and Materials ScienceNanchang UniversityNanchang 330031China Institute of high Energy Physics Chinese Academy of SciencesBeijing 100049China

Theories of modified gravity suggest that the propagation speed of gravitational waves(GW)v_gmay deviate from the speed of light c.A constraint can be placed on the difference between c and v_gwith a simple method that uses the arrival time delay between GW and electromagnetic wave simultaneously emitted from a burst *** simulated the joint observation of GW and short gamma-ray burst signals from binary neutron star merger events in different observation campaigns,involving advanced LIGO(aLIGO)in design sensitivity and Einstein Telescope(ET)joint-detected with Fermi/*** a result,the relative precision of constraint on v_gcan reach~10~(-17)(aLIGO)and~10^(-18)(ET),which are one and two orders of magnitude better than that from GW170817,*** continue to obtain the bound of graviton mass m_g≤7.1(3.2)×10~(-20)eV with aLIGO(ET).Applying the Standard-Model Extension test framework,the constraint on v_gallows us to study the Lorentz violation in the nondispersive,nonbirefringent limit of the gravitational *** obtain the constraints of the dimensionless isotropic coefficients S_(00)^(4)at mass dimension d=4,which are-1×10^(-15)

关键词： gravitational waves-(stars)gamma-ray burst general-stars neutron

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Intermediate-mass black holes in Green pea galaxies(IMBH-GP) I:A candidate sample from LAMOST and SDSS

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Science China(Physics,Mechanics & Astronomy) 2024年第10期Mechanics & Astronomy) .卷 151-165页

作者： Ruqiu Lin Zhen-Ya Zheng Fang-Ting Yuan Jun-Xian Wang Chunyan Jiang Ning Jiang Lingzhi Wang Linhua Jiang Xiang Ji Shuairu Zhu Xiaodan Fu Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical ObservatoryChinese Academy of Sciences school of Astronomy and Space sciences University of Chinese Academy of Sciences CAS Key Laboratory for Research in Galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of China Chinese Academy of sciences South America Center for Astronomy (CASSACA) National Astronomical ObservatoriesChinese Academy of Sciences CAS Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of Sciences Kavli Institute for Astronomy and Astrophysics Peking University Department of Astronomy School of PhysicsPeking University

The scaling relation of central massive black holes（MBHs） and their host galaxies is well-studied for supermassive BHs(SMBHs,MBH≥10～6M⊙).However,this relation has large uncertainties in the mass range of the intermediate-mass BHs(IMBHs,MBH～10～3-10～6M⊙).Since Green pea（GP） galaxies are luminous compact dwarf galaxies,which may be likely to host less massive SMBHs or even IMBHs,we systematically search for MBHs in a large sample of 2190 GP galaxies at z<0.4,selected from LAMOST and SDSS spectroscopic ***,we report a newly discovered sample of 59 MBH candidates with broad Hα *** sample has a median stellar mass of 108.83±0.11M⊙and hosts MBHs with single-epoch virial masses ranging from MBH～104.7to 108.5M⊙(median 105.85±0.64M⊙).Among the 59 MBH candidates,36 have black hole masses MBH≤10～6M⊙（IMBH candidates）,one of which even has MBH■10～5M⊙.We find that the MBH-M*relation of our MBH sample is consistent with the MBH-Mbulgerelation for SMBHs,while is above the MBH-M*relation for MBHs in dwarf galaxies in the same mass ***,we show that 25 MBH candidates,including 4 IMBH candidates,have additional evidence of black hole activities,assessed through various methods such as the broad-line width,BPT diagram,mid-infrared color,X-ray luminosity,and radio *** studies show that it is very promising to find IMBHs in GP galaxies,and the BH sample so obtained enables us to probe the connection between the MBHs and compact dwarf galaxies in the low-redshift Universe.

关键词： SMBHs IMBHs Green pea galaxies compact dwarf galaxies

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Superconducting,Topological,and Transport Properties of Kagome Metals CsTi_(3)Bi_(5)and RbTi_(3)Bi_(5)

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Research 2024年第2期2023卷 753-762页

作者： Xin-Wei Yi Zheng-Wei Liao Jing-Yang You Bo Gu Gang Su school of Physical sciences University of Chinese Academy of SciencesBeijing 100049China Department of Physics Faculty of ScienceNational University of Singapore117551Singapore Kavli Institute for Theoretical sciences and CAS Center for Excellence in Topological Quantum ComputationUniversity of Chinese Academy of SciencesBeijing 100190China

The recently discovered ATi_(3)Bi_(5)(A=Cs,Rb)exhibit intriguing quantum phenomena including superconductivity,electronic nematicity,and abundant topological ***_(3)Bi_(5)present promising platforms for studying kagome superconductivity,band topology,and charge orders in parallel with *** this work,we comprehensively analyze various properties of ATi_(3)Bi_(5)covering superconductivity under pressure and doping,band topology under pressure,thermal conductivity,heat capacity,electrical resistance,and spin Hall conductivity(SHC)using first-principles *** superconducting transition temperature(Tc)of CsTi_(3)Bi_(5)and RbTi_(3)Bi_(5)at ambient pressure are about 1.85 and 1.92 *** subject to pressure,Tc of CsTi_(3)Bi_(5)exhibits a special valley and dome shape,which arises from quasi-two-dimensional compression to three-dimensional isotropic compression within the context of an overall decreasing ***,Tc of RbTi_(3)Bi_(5)can be effectively enhanced up to 3.09 K by tuning the kagome van Hove singularities(VHSs)and flat band through *** can also induce abundant topological surface states at the Fermi energy(EF)and tune VHSs across ***,our transport calculations are in excellent agreement with recent experiments,confirming the absence of charge density ***,SHC of CsTi_(3)Bi_(5)can reach up to 226h·(e·Ω·cm)^(-1)at *** work provides a timely and detailed analysis of the rich physical properties for ATi_(3)Bi_(5),offering valuable insights for further experimental verifications and investigations in this field.

关键词： doping superconductivity conductivity

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Progress and perspective on rechargeable magnesium-ion batteries

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Science China Chemistry 2024年第1期67卷 214-246页

作者： Guixin Wang Zhechen Wang Hucheng Shi Aobing Du Mingliang Sun Guanglei Cui school of Materials Science and Engineering Ocean University of ChinaQingdao 266100China Qingdao industrial Energy Storage Research Institute Qingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao 266101China

Current electrochemical energy storage technology has evolved a variety of rechargeable battery ***,the resource shortage of raw materials in commercially available lithium-ion batteries has attracted widespread *** requirements to meet resourcefulness,sustainability,safety,and high energy density have motivated the development of rechargeable magnesium-ion batteries(RMBs).Although RMBs have made significant progress so far,there are still many obstacles to practical *** systematically summarize the significant progress and the latest research on RMBs,including Mg^(2+)-conducting electrolytes,Mg^(2+)-storage cathodes,and Mg-based *** this review,we mainly introduce the properties and features of various Mg^(2+)-conductive electrolytes,the mainstream cathode materials,and their respective Mg^(2+)-storage mechanisms,as well as the Mg metal(or alloy)anodes and the corresponding modification ***,the future directions in various key components for RMBs are highlighted.

关键词： rechargable magenisum-ion batteries electrolytes cathodes anodes

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Electrochemical CO_(2)reduction to C_(2+)products over Cu/Zn intermetallic catalysts synthesized by electrodeposition

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Frontiers in Energy 2024年第1期18卷 80-88页

作者： Ting DENG Shuaiqiang JIA Shitao HAN Jianxin ZHAI Jiapeng JIAO Xiao CHEN Cheng XUE Xueqing XING Wei XIA Haihong WU Mingyuan HE Buxing HAN school of Chemistry and Molecular Engineering East China Normal UniversityShanghai 200062China Institute of Eco-Chongming Shanghai 202162China Institute of high Energy Physics Chinese Academy of SciencesBeijing 100049China Institute of Chemistry Chinese Academy of SciencesBeijing 100190China

Electrocatalytic CO_(2)reduction(ECR)offers an attractive approach to realizing carbon neutrality and producing valuable chemicals and fuels using CO_(2)as the ***,the lack of cost-effective electrocatalysts with better performances has seriously hindered its ***,a one-step co-electrodeposition method was used to introduce Zn,a metal with weak^(*)CO binding energy,into Cu to form Cu/Zn intermetallic catalysts(Cu/Zn IMCs).It was shown that,using an H-cell,the high Faradaic efficiency of C_(2+)hydrocarbons/alcohols()could be achieved in ECR by adjusting the surface metal components and the applied *** suitable conditions,FEC_(2+)and current density could be as high as 75%and 40 mA/cm^(2),*** with the Cu catalyst,the Cu/Zn IMCs have a lower interfacial charge transfer resistance and a larger electrochemically active surface area(ECSA),which accelerate the ***,the^(*)CO formed on Zn sites can move to Cu sites due to its weak binding with*CO,and thus enhance the C–C coupling on the Cu surface to form C_(2+)products.

关键词： carbon dioxide electroreduction electrochemistry co-electrodeposition intermetallic catalysts value-added chemicals

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The quantum Ising model for perfect matching and solving it with variational quantum eigensolver

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Science China(Information sciences) 2024年第9期67卷 306-320页

作者： Qilin ZHENG Pingyu ZHU Chao WU Miaomiao YU Weihong LUO Ping XU Institute for Quantum Information and State Key Laboratory of high Performance Computing College of Computer Science and Technology National University of Defense Technology Hefei national Laboratory

Obtaining all perfect matchings of a graph is a tough problem in graph theory, and its complexity belongs to the #P-Complete class. The problem is closely related to combinatorics, marriage matching problems, dense subgraphs, the Gaussian boson sampling, chemical molecular structures, and dimer *** this paper, we propose a quadratic unconstrained binary optimization formula of the perfect matching problem and translate it into the quantum Ising model. We can obtain all perfect matchings by mapping them to the ground state of the quantum Ising Hamiltonian and solving it with the variational quantum eigensolver. Adjusting the model's parameters can also achieve the maximum or minimum weighted perfect matching. The experimental results on a superconducting quantum computer of the Origin Quantum Computing Technology Company show that our model can encode 2~n dimensional optimization space with only O（n） qubits consumption and achieve a high success probability of the ground state corresponding to all perfect matchings. In addition, the further simulation results show that the model can support a scale of more than 14 qubits, effectively resist the adverse effects of noise, and obtain a high success probability at a shallow variational depth. This method can be extended to other combinatorial optimization problems.

关键词： perfect matching Ising model quantum Hamiltonian variational quantum eigensolver quadratic unconstrained binary optimization

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A Physics‑Based Seismic Risk Assessment of the Qujiang Fault:From Dynamic Rupture to Disaster Estimation

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International Journal of Disaster Risk Science 2024年第1期15卷 165-177页

作者： Yilong Li Zijia Wang Zhenguo Zhang Yuhao Gu Houyun Yu school of national Safety and Emergency Management Beijing Normal UniversityZhuhai 519087China Department of Earth and Space sciences Southern University of Science and TechnologyShenzhen 518055China Guangdong Provincial Key Laboratory of Geophysical high-Resolution Imaging Technology Southern University of Science and TechnologyShenzhen 518055China

This study achieved the construction of earthquake disaster scenarios based on physics-based methods-from fault dynamic rupture to seismic wave propagation-and then population and economic loss *** physics-based dynamic rupture and strong ground motion simulations can fully consider the three-dimensional complexity of physical parameters such as fault geometry,stress field,rock properties,and *** analysis of multiple seismic disaster scenarios along the Qujiang Fault in western Yunnan Province in southwestern China based on different nucleation locations was *** results indicate that the northwestern segment of the Qujiang Fault is expected to experience significantly higher levels of damage compared to the southeastern ***,there are significant variations in human losses,even though the economic losses are similar across different *** Bai Autonomous Prefecture,Chuxiong Yi Autonomous Prefecture,Yuxi City,Honghe Hani and Yi Autonomous Prefecture,and Wenshan Zhuang and Miao Autonomous Prefecture were identified as at medium to high seismic risks,with Yuxi and Honghe being particularly *** targeted earthquake prevention measures in Yuxi and Honghe will significantly mitigate the potential risks posed by the Qujiang ***,although the fault is within Yuxi,Honghe is likely to suffer the most severe *** findings emphasize the importance of considering rupture directivity and its influence on ground motion distribution when assessing seismic risk.

关键词： Earthquake disaster loss estimation Physics-based earthquake scenario simulation Qujiang Fault Rupture directivity Seismic risk assessment

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high-power all-fiber linearly polarized Yb-doped chirped pulse amplifier based on active polarization control

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Chinese Optics Letters 2024年第4期22卷 66-70页

作者：王涛任帅常洪祥任博郭琨李灿马鹏飞冷进勇周朴 College of Advanced Interdisciplinary Studies National University of Defense TechnologyChangsha 410073China school of Information and Communications National University of Defense TechnologyWuhan 430035China Nanhu Laser Laboratory National University of Defense TechnologyChangsha 410073China Hunan Provincial Key Laboratory of high Energy Laser Technology National University of Defense TechnologyChangsha 410073China

high-power ultrafast laser amplification based on a non-polarization maintaining fiber chirped pulse amplifier is *** active polarization control technology based on the root-mean-square propagation(RMS-prop)algorithm is employed to guarantee a linearly polarized output from the system.A maximum output power of 402.3 W at a repetition rate of 80 MHz is realized with a polarization extinction ratio(PER)of>11.4 *** addition,the reliable operation of the system is verified by examining the stability and noise properties of the amplified *** M2factor of the laser beam at the highest output power is measured to be less than 1.15,indicating a diffraction-limited beam ***,the amplified laser pulse is temporally compressed to 755 fs with a highest average power of 273.8 *** is the first time,to the best of our knowledge,that the active polarization control technology was introduced into the high-power ultrafast fiber amplifier.

关键词： active polarization control root-mean-square propagation algorithm linearly polarized laser chirped pulse amplification femtosecond laser fiber laser

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